The Investigation of Dynamic properties Effects on the Seismic Behavior of Duplex Reinforced Concrete Structures Strengthened with FRP Sheets

Many concrete structures do not meet the provisions of new regulations due to the reasons such as duplex structures and there is not direct suggestion given by provisions, so it is necessary to provide strengthening and rehabilitation methods such structures among which the use of FRP sheet. In this paper, the seismic behavior of regular and duplex reinforced concrete buildings non-strengthened and strengthened with CFRP was studied via non-linear analyses fifty buildings with 3, 5,10 and 15 stories with the span number of 1-5. Different parameters such as the maximum displacement of the structure, drift, the shear force applied on the stories, the performance points and the structure capacity curve have been studied and the structure strengthening effect and the structure making duplex effect and the height increase effect and the number of spans were investigated. The results indicated that confining the beams and columns of the reinforced concrete structure with CFRP increased the area under the pushover curve which indicates the structure depreciated energy. Even more the initial gradient and stiffness of the strengthened structure were 1.5-2.5 times more than those of original structure. Generally, 5- story building showed better behavior in terms of maximum stiffness and minimum displacement, and 15- story building showed the best performance in terms of greater energy absorption comparing the other structures. By comparing the capacity curves of the regular and duplex buildings, it can be expressed that the maximum initial stiffness and the minimum lateral displacement belong to the duplex model.